1. Field of the Invention
The present invention relates to recording apparatuses, and more particularly, to a technology suitable for recording data onto a recording medium by irradiating the recording medium with an optical beam.
2. Description of the Related Art
Recording apparatuses for recording and playing back various types of information data, such as moving image data, by irradiating an optical disk with a laser beam have been known. In order to record data onto an optical disk, a laser power that is higher than the laser power used for playing back the data is necessary. If the laser power used for recording is not sufficient, writing becomes unstable and an increased number of errors may be found in playback data. In contrast, if a higher laser power is used for recording, writing can be successfully performed. However, since the effective diameter of a laser beam is large in such a case, neighboring data recorded in the vicinity may not be played back accurately.
Thus, laser power to be used for recording must be set to an optimal value. Under such circumstances, a magneto-optical disk apparatus for adjusting laser power to be applied to an optical disk is disclosed, for example, in Japanese Patent Laid-Open No. 8-7369.
In addition, in the case of recording data onto an optical disk, the optical disk must be rotating stably at a predetermined speed. Thus, in order to record data onto an optical disk accurately, rotation control for causing the optical disk to rotate stably at a predetermined speed, as well as adjustment of laser power, is required.
In addition, in recent years, due to an improvement in the data record rate for optical disks, writing to an optical disk can be achieved at a record rate that is several times faster than a rate of storing data to be recorded to a memory. Thus, for example, in the case of recording moving image data onto an optical disk, a configuration in which, when the amount of moving image data temporarily stored in a memory reaches a predetermined value, the stored moving image data is read from the memory and written to the optical disk, is normally adopted.
FIGS. 10A to 10C are illustrations each showing a change in the amount of moving image data stored in a memory. In the examples shown in FIGS. 10A to 10C, the data write rate for an optical disk is higher than the data storage rate for the memory.
Thus, as shown in FIG. 10A, after writing of data to the optical disk is started, the amount of data stored in the memory gradually decreases. Then, at a point in time when the amount of data stored in the memory becomes smaller than a writing stop threshold, which is used for stopping writing, writing to the optical disk is stopped.
In the case of intermittently writing data to an optical disk as described above, processing, such as adjustment of the recording position on the optical disk, as well as the actual data writing operation, is required. During such a processing period, data writing cannot be performed, resulting in wasted time. Thus, in the case of intermittently writing data as described above, increasing the amount of data to be written in a single recording operation may reduce an amount wasted time.
However, writing of moving image data cannot be started until an optical disk rotates at a desired speed, and moving image data during such a waiting time period is stored in a memory. In addition, an optimal laser power varies depending on the temperature of an optical disk. Thus, when the temperature of the optical disk changes, laser power must be adjusted before data writing is started.
Consequently, during the period in which adjustment of laser power is performed, data writing cannot be performed. Thus, moving image data during such an adjustment period is stored in the memory.
As a result, as shown in FIG. 10C, writing to the disk cannot be started at time 1004 when the amount of data stored in the memory exceeds a writing start threshold, which is used for starting writing, thus causing overflow of moving image data. Thus, a memory having a larger capacity is necessary. This causes a problem of an increase in the cost of an apparatus.
It is desirable that, while recording is stopped, rotation of the optical disk is stopped to reduce power consumption.
Thus, in a case where a recording operation is performed for the first time since the start of recording, a long time is required to achieve a desired rotation speed of an optical disk compared with the second and subsequent recording operations. In contrast, in a case where the second and subsequent writing operations are performed based on intermittent recording, a desired speed can be achieved quickly compared with the first writing operation.
In addition, adjustment of laser power is not necessarily performed before data writing is started. The adjustment of laser power can be performed only in a case where a large temperature change occurs. As described above, it is not desirable to prepare a large-capacity memory only for laser power adjustment or for performance of the first writing operation.
Thus, as described above, in order to prevent overflow of moving image data in a memory, a threshold for starting writing to an optical disk may be set to a low level.
However, if the threshold for starting writing is set to a low level, writing start and writing stop are frequently repeated, as shown in FIG. 10B.
This causes a problem in which the duration of a period required to perform processing, such as adjustment of a recording position on an optical disk, increases.